Petroleum System Analysis in the Central Part of the West Siberian Basin
Kuznetcova, Marina 1999-
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The West Siberian Basin is one of the largest hydrocarbon provinces in the world. The basin began to evolve 251 Ma as a result of Permo-Triassic trap magmatism and subsequent large-scale thermal subsidence. In the Triassic, sedimentation started and the basin was subdivided into two main layers: the crystalline basement and the sedimentary cover. The study area is located in the central part of the West Siberian Basin. The sedimentary cover in the considered territory is penetrated by many faults and subdivided into a large number of tectonic structures. The petroleum system of the study area is investigated here by analyses of source rocks, reservoirs, seals, and 1D and 2D-basing modeling approach. These methods allowed estimate of the presence of three source rocks: the Lower Jurassic (Radom Formation), Middle Jurassic (Tyumen Formation), and the Upper Jurassic-Lower Cretaceous (Bazhenov Formation). Major reservoirs of the petroleum system are referred to Lower Cretaceous deposits. In addition, the petroleum system is characterized by migration pathways, which are located both in and out of faults, traps (anticlinal and tectonic), seals, and overburden rocks, which compact underlying source rocks. Moreover, both 1D and 2D modeling allowed estimates of the timing of essential petroleum-system processes: trap and reservoir formation, generation, expulsion, migration, accumulation and entrapment, and preservation. The results show that the reservoirs were formed during the Lower Jurassic-Lower Cretaceous; the onset of trap formation occurred in the Lower Jurassic and continued till the end of the Lower Cretaceous; hydrocarbons have been generated since the Upper Cretaceous in the Radom and Tyumen Formations and since the Paleocene in the Bazhenov Formation; expulsion, migration, accumulation, and preservation began in the Oligocene in the Radom Formation and in the Miocene in the Tyumen and Bazhenov Formations and are currently continuing. The results of 2D modeling indicate four potentially productive areas along three seismic profiles. However, 3D seismic, Frequency-Dependent Processing and Interpretation (FDPI), extra geological and geochemical data are necessary for creation of a 3D model in order to better evaluate commercial viability of the petroleum system.